Looks like Fatoua villosa, an herb in the Moraceae. Not something you
want to encourage. Compare
http://pubs.caes.uga.edu/caespubs/pubcd/C867-5.htm

M. Reed

wrote:
WOndering if anyone recognizes this weedy plant. Lots of seedlings just
appeared this year and I let a couple grow to try to see what it might be.
About 60cm tall.

It's growing in the Washington, DC area.

http://www.flickr.com/photos/67073460@N00/3864244091/

http://www.flickr.com/photos/67073460@N00/3864244071/